Pre-sterilized, single-use bag manifolds such as those used in bio-pharmaceutical production (see U.S. Pat. No. 6,712,963, incorporated here by reference) lack the ability to monitor and validate important, analytical solution parameters during the processing of biopharmaceutical solutions. The use of such bag manifolds, for example, in preparative chromatography or tangential flow filtration (TFF) or fluid transfer generally, is severely limited by the general lack of pre-sterilized, pre-calibrated, pre-validated in-line sensors and detectors
In-line, flow through-type sensors and detectors are well known in industry and are extensively used in analytical laboratories, pilot plants and production facilities. In-line conductivity detectors, in particular, are used in ion chromatography, preparative chromatography, flow injection analysis (FIA), tangential flow filtration (TFF), as well as water purity analysis. However, prior-art in-line flow through conductivity sensors and detectors are typically made out of machined, stainless steel or plastic materials. These sensors and detectors are intended for permanent installations and long-term use. Prior-art in-line sensors and detectors are difficult to sterilize, require in-field calibration and validation by an experienced operator before use, and are very expensive, often costing thousands of dollars. Consequently, prior art sensors and detectors are not suited for a single-use sensor application.
The use of a memory device imbedded in disposable clinical sensors has been reported. For example, U.S. Pat. No. 5,384,028 deals with the fabrication of an enzyme-based glucose biosensor that utilizes a sensor-imbedded data memory device. However, this patent utilizes barcodes and memory devices for purposes of sensor traceability and inventory control. Furthermore, this patent requires sensor calibration and/or validation by the clinician immediately prior to each use.
In line sensors for use in bioprocessing applications must be designed to meet government regulations regarding device traceability and validation. In addition, in-line sensors must meet the application requirements for accuracy and precision. These requirements present extra challenges and pose unique problems when the in-line sensor is to be disposable and suitable for single use as desired. Another problem is how to provide disposable in-line sensors that are pre-calibrated. Also for aseptic sensor applications, each single-use sensor, must meet sterilization requirements. Furthermore, single-use sensors must meet economic requirements, i.e. sensors must be low cost, easy to replace with negligible disposal expense.
Meeting sensor sterilization requirements represents another very significant sensor design challenge. This is especially the case, when the sensor is intended for single-use bag manifold applications such as those described in the U.S. Pat. No. 6,712,963 (which is incorporated herein by reference). The biotechnology and bio-pharmaceutical industries utilizes four different sterilization methods: (1) autoclaving (i.e. timed exposure to pressurized steam at approximately 125° Celsius); (2) time-limited exposure to an ethylene oxide gas; (3) gamma ray irradiation up to 50 kGy; and (4) electron-beam irradiation.
For many single-use sensor application, e.g. for bag manifolds, the preferred sterilization method by the industry is by gamma or electron-beam irradiation. The main advantage of gamma and electron-beam irradiation lies is that the entire, pre-assembled manifold, including bags, tubing, connectors and sensors, can be first sealed in a shipping bag and then exposed to sterilizing radiation or electron-beam bombardment. The entire manifold assembly within the shipping bag remains sterile for a rated period, unless the shipping bag is comprised during shipment or storage.